Prior to the present invention, poly(vinyl alcohol) (hereinafter referred as "PVA") has traditionally been handled in its dry, particulate form. The water soluble forms of PVA are known to be 77 to 99.8% hydrolyzed. Problems associated with dry PVA include undesirable dust generation, poor dispersibility when added to aqueous systems, and undesirably long dissolution times.
The dust associated with dry, particulate PVA presents the same conventional handling problems as are encountered with other particulate materials.
When added to aqueous systems, PVA tends to agglomerate to form clumps. Agglomeration can be reduced in many cases by adding the polymer to the aqueous system slowly with agitation. Slow dissolution substantially reduces the speed of manufacturing operations.
For the above reasons, plant operators desire a fast, effective, and simple way of incorporating PVA into an aqueous system. In other words, users of PVA desire a stable, concentrated, PVA suspension that can be used to incorporate PVA into aqueous solutions readily, without formation of agglomerates or clumps, and which may be handled without the problems associated with a dry powder.
Several formulations exist in the prior art that describe suspension systems of various water soluble polymers that avoid the above mentioned problems. For example, U.S. Pat. No. 4,883,536 discloses an aqueous suspension of at least 15% by total weight of the suspension, of at least one anionic or nonionic water-soluble polymer dispersed in an aqueous solution of an ammonium salt having a multivalent anion, wherein the weight ratio of the ammonium salt to the water is at least 0.15. Another example is U.S. Pat. No. 4,883,537 that discloses the use of potassium carbonate in aqueous suspensions of sodium carboxymethylcellulose.
The present invention overcomes the above mentioned problems in industrial practice in a different manner than the above prior art by using different types of salts for preparing fluidized suspensions of PVA.